An inductor with mounting means

ABSTRACT

A mounted multi-lead circuit element having a plurality of leads for separate external connection comprising segments of a strip of relatively stiff insulating material having stiff parallel terminal wires secured thereacross and extending beyond said strip at both ends secured directly or indirectly to the circuit element or wrapped thereabout in supporting relation to provide at least as many of said wires as there are of said leads, the leads being secured to one end of the terminal wires and the other ends of the terminal wires being available for connection into a circuit.

United States Patent [191 Renskers et al.

[ 1 July 3,1973

[ AN INDUCTOR WlTl-l MOUNTING MEANS [75] Inventors: John O. Renskers,Crystal Lake; Charles S. Liebman, McHenry;

Robert J. Salzman, Woodstock; Charles E. Schroeder, Mundelein, all

[73] Assignee: Coilcraft, Inc., Cary, Ill.

[22] Filed: Oct. 5, 1970 21 Appl. No.: 77,875

Related US. Application Data [62] Division of Ser. No. 634,789, March 6,1967, Pat. No. 3,534,309, which is a division of Ser. No. 387,139, Aug.3, 1964, Pat. No. 3,368,276.

[52] US. Cl. 336/192, 336/65, 336/208 [51] Int. Cl. ..H0lf 15/10 [58]Field of Search 336/65, 198, 208, 336/209, 192; 174/117 F, 117 FF, 117 A[56] References Cited UNlTED STATES PATENTS 2,355,477 8/1944 Stahl336/198 X 2,486,751 11/1949 McMichael 336/192 X 2,511,174 6/1950 Osborne336/198 Henderson ass/209 2,858,514 10/1958 Henderson....

2,864,064 12/1958 Heaton 336/65 2,902,661 9/1959 Henderson 33612093,131,371 4/1964 Brekke 336/198 X FOREIGN PATENTS OR APPLICATIONS198,739 6/1923 Great Britain 174/117 A 997,508 7/1965 Great Britain....

1,319,821 4/1962 France 174/117 A Primary Examiner-E. A. GoldbergAttorney- Howard H. RogersJr.

[57] ABSTRACT 3 Claims, 30 Drawing Figures AN INDUCTOR WITH MOUNTINGMEANS CROSS REFERENCE TO RELATED APPLICATIONS This application is adivision of Ser. No. 634,789 filed Mar. 6, 1967, now U.S. Pat. No.3,534,309 dated Oct. 13, 1970, which in turn is a division of Ser. No.387,l39, filed Aug. 3, 1964, now U. S. Pat. No. 3,368,276 and issuedFeb. 13, 1968, both applications being filed under the title of MOUNTFOR CIRCUIT ELEMENTS by John O. Renskers et al., the earlier patentissuing as A Method for Mounting a Circuit Element in the name of JohnO. Renskers sole.

BACKGROUND OF THE INVENTION The present invention relates to a mount forelectric and electronic circuit elements or, more narrowly, for coilsand transformers and to coils, etc. so mounted for insertion intoelectronic and electric circuitry.

A mounted coil somewhat similar to the invention hass been devisedwherein staples are driven into the edge of a rectangular stiff paperboard and the staple ends then splayed out to extend beyond the edges ofthe paper. A coil is glued to the face of the paper between the staplesand the coil leads are wrapped around the staple ends projecting beyondone edge of the paper.

There are several difficulties with this construction. Since theattaching wires are inserted in a true stapling fashion, i.e., the wiresare bent into a U-shape and the ends of the wires driven through thepaper material, the wire ends must be equal and somewhat limited inlength. That is, the legs of a paper staple to be inserted by ordinarystapling machinery must be the same length and they must be short enoughso as to have the necessary rigidity so that a blow on the back side ofthe staple will punch the legs through the material in which they are tobe inserted and not bend them. Likewise, gluing a coil to the face ofthe material between the staples is a time consuming and therefore anexpensive operation. The glue must be applied, the coil deposited on theglued patch, and the assembly thereupon set aside to dry for a certainperiod of time. The gluing operation calls for a substantial number ofsteps, the drying time is expensive, and the glued construction isgenerally unsuited to automation.

SUMMARY OF THE INVENTION The coil form of the invention is directed tothe improvement of this structure to avoid these disadvantages. The formof the invention requires no symmetry of terminal wire ends and imposesno limitations on the length thereof. It avoids a gluing operation forcementing the coil to the form. The form of the invention is highlyversatile and capable of mounting many circuit components in differentconfigurations to meet various purposes. Its adaptation to these variousconfigurations is simple and easy.

Many materials may be employed in the construction of formsincorporating the invention and, with these different materials, theinvention is capable of several embodiments, all of which, however,enjoy the same advantage as that described above, of unsymmetricalterminal wires, an indefinite length of terminal wires, accuracy ofterminal wire location for purposes of automated circuit boardinsertion, and exceedingly low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of acompleted mounted coil illustrating one embodiment of the invention;

FIG. 2 is a section taken along the line 2-2 of FIG. 1, looking in thedirection of the arrows;

FIG. 3 is a front elevation of a mounted coil illustrating anotherembodiment of the invention;

FIG. 4 is a section taken along the line 4-4 of FIG. 3 looking in thedirection of the arrows;

FIG. 5 is a front elevation of another form of coil mount;

FIG. 6 is a plan view of the mount of FIG. 5 taken from the line 6-6 ofFIG. 5, looking in the direction of the arrows;

FIG. 7 is a front elevation of another form of coil mount;

FIG. 8 is a side elevation of the mount of FIG. 7 taken from the leftside thereof;

FIG. 9 is a section through an appropriate set of dies whereby the mountof FIG. 7 is formed showing a terminal wire in elevation on top of amount board in section;

FIG. 10 is a view similar to FIG. 9 showing the first step in theformation of the mount;

FIG. 11 is a section along the line 11-11 of FIG. 10 showing the stageof operation of FIG. 10;

FIG. 12 is a view similar to FIG. 11 showing a second stage in theformation;

FIG. 13 is a view similar to FIG. 11 showing the concluding stage in theformation;

FIG. 14 is a front elevation of one form of mounting board adapted forthe attachment of a coil thereto;

FIG. 15 is a similar view of the board of FIG. 14 showing a highinductance coil, partly in section, mounted thereto;

FIG. 16 is a section taken along the line 16-16 of FIG. 15;

FIG. 17 is a view similar to FIG. 16 showing a low inductance coilmounted therein;

FIG. 18 is a front elevation of a mounting board adapted for theattachment of a medium inductance, universally would coil;

FIG. 19 is a section taken along the line 19-19 of FIG. 18 looking inthe direction of the arrows showing a coil mounted therein;

FIG. 20 is a front elevation of a mounting board having an alternativeform of coil attaching means; 7

FIGS. 21, 22 and 23 are sections taken along the line 21-21 of FIG. 20showing optional ways of attaching coils to the board of FIG. 20;

FIG. 24 is a front elevation of a mounting board incorporating a thirdprovision for coil retention;

FIG. 25 is a section taken along the line 25-25 of FIG. 24 looking inthe direction of the arrows showing a coil mounted thereto;

FIG. 26 is a side elevation of the mount of the invention used in a fourterminal context;

FIG. 27 is a section along the line 27-27 of FIG. 26 looking in thedirection of the arrows;

FIG. 28 is a modified form of a mount adapted substantially for fullenclosure of a coil or circuit element and, optionally, for six terminalconnection;

FIG. 29 is a section through a mounted coil employing the mount of FIG.28 and may be considered generally as being taken along the line 29-29of FIG. 28 looking in the direction of the arrows; and

FIG. 30 is a front elevation of a coil wherein the mounting board itselfserves as a coil form.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As will be apparent from thedrawings viewed collectively and referring particularly to FIG. 1, themounted coil of the invention consists first of a generally squaremounting board having two relatively stiff terminal wires 12 adjacentopposite edges of the board and extending beyond the board at one end 14only a short distance and at the other end 16 a substantial distance. Amaterial which we have used for the mounting board which meets ourpurposes excellently is an electrical grade vulcanized fibre known inthe trade as fish paper. Such a material is sold under the trademarkArmite, a mark of the Spaulding Fibre Company of Tonawanda, New York.This paper is a dense relatively stiff composition board. Othercardboard-like insulating materials may be employed however as long asthey possess a certain minimum degree of stiffness.

A coil or other circuit element 18 is secured to the center of themounting board. In the case of FIGS. 1, 3 and 17 this circuit element isa single layer coil 20 wound on a tubular form 22 which is pressed intoa window 24 formed in the mounting board 10. The leads 26 of the coilare wrapped tightly around the short ends 14 of the terminal wiresimmediately above the mounting board, and the coil as thus mounted isdipped into a bathof a suitable protective coating 28 to protect andinsulate the circuit element, to bind all parts firmly together and toimpart rigidity to the mounted coil. Desirably the dip will be such asto immerse the mounting board totally but leave the lower long ends 16of the terminal wires 12 uncoated. A phenol formaldehyde coatingcomposition identified in the trade as Durez (a trademark of the DurezPlastics & Chemicals Co.) has been found to be highly satisfactory. TheDurez comes as an uncured powder. A thick solution or suspension inalcohol or acetone is made, the mounted coils dipped and permitted todry and then baked to cure the resin. The Durez forms a hard and strongcoating over the entire mounting board, coil, and adjacent areas of theterminal wires, encapsulating the entire unit and fixing the relativepositions of the various parts and making rigid the mounting board. Itwill be appreciated that, with the Durez encapsulation, the assemblageof the coils prior to dipping may be weak or fragile. Strength onlysufficient to hold the members in place in the successive steps of wireinsertion, coil mounting, coil lead connection, dipping, etc. andincidental handling is needed.

Although the Durez coating is shown only in FIGS. 1 and 2, it will beappreciated that it may be employed to obtain the several advantages inany of the modifications illustrated, and its omission from theillustrations of other modifications is simply to make clear theinternal structure of the mounted coils.

As stated above, the method of inserting the terminal wires employed inthe art has been by a conventional stapling step wherein the wire isbent into a U-shape and the free ends of the wire are then driventhrough the mounting board and the feet thereafter splayed out. Thisimposes two limitations; first, that the legs of the staple must beequal in length and second, that the legs of the staple cannot be long.It also imposes a limitation corollary to the second limitation that themounting board material must be easily penetrated.

As an improvement over this construction we have devised the coil mountillustrated particularly in FIGS. 7 and 8 and a method of making it inFIGS. 9 through 13. In FIG. 7, we show a mounting board 30 as describedabove with terminal wires 32 attached thereto, short ends 34 projectingfrom one side of the board and long ends 36 beyond the opposite side. Asin conventional stapling, the end portions 34 and 36 of the wires lie onone side of the board and a central portion or bight 38 lies on theother side of the board. The method which makes possible the disparityof terminal wire end lengths is the step of driving the bight of theterminal wire through the board to effect this relation rather thandriving the ends of the terminal wire through the board.

In this construction the use of the fish paper or equivalent paper stockis highly desirable. It has stiffness and strength sufficient to effecta good retention of the terminal wires. The mounting board may beslotted as at 40 for the reception of the wire bights or the centralportion of the wire may be driven through the unslotted board materialto break its own way. In either case the fish paper has sufficientresilience to snap back into plane after the passage of the bight of theterminal wire therethrough and so effect the desired retention of theterminal wire.

Illustrative mechanism is shown in FIGS. 9 through 13. In these figureswe show upper and lower clamping members 42 and 44 which are adapted toengage substantially the entire surface of the mounting board aside fromthe line of operation involved in the terminal wire insertion. The upperclamping member is centrally vertically slotted for the reception of atongue 46 about equal in thickness to the diameter of the terminal wire.The tongue is movable up and down relative to the upper clamping member.The upper clamping member is likewise grooved at 48 on its bottom facein line with tongue 46 for the reception of a terminal wire.

The bottom clamp 44 likewise has a slot therein in alignment with andwider than the slot in the upper clamping member for the reception of avertically reciprocable die member 50 somewhat wider than the tongue 46.

The mounting board 30 is placed on the lower clamping member and aterminal wire 32 placed thereon. The upper clamping member is thenbrought down to clamp securely the mounting board and retain theterminal wire in its proper position across the mounting board.Thereafter the tongue 46 is moved downward to drive the central portionor bight 38 of the terminal wire through the mounting board. As stated,the mounting board may be slotted for the passage of the wire bight orthe bight may tear its own way through. In either case the configurationwill-be generally as shown in FIGS. ll) and 11. The tongue 46 is thenretracted to permit the bent-down edges of the torn or preformed slot inthe fish paper to return to a position near their original plane behindthe bight 38 of the terminal wire as shown in FIG. 12. Thereafter thelower die 50 is raised to flatten the bight of the terminal wire againstthe under side of the slot in the fish paper.

Although we have illustrated the insertion of a single wire only, itwill be evident that the mechanism of FIGS. 943 may be duplicated toinsert both wires simultaneously or even further multiplied for theinsertion of several wires, as with some modifications described below.Simultaneously with this operation, ap propriate dies can be used toshape the exterior outline of the mounting board, to score the paper asdesired, and to fashion windows therein as will be later described.Following completion, the upper clamping member 42 is raised to releasethe completed coil mount.

The mechanism described here is purely illustrative, but it is wellsuited to automatic and rapid operation. The fish paper may be suppliedin strips and the terminal wires supplied from coils mountedtransversely to the line of travel of the strips. The cutting to lengthof the ends of the terminal wires can likewise be performedsimultaneously with the assembly procedure. Thus, the wire could be fedagainst a stop 49, and a shear S1 acting against an anvil 53 could movewith the upper clamping member 42 to do the cutting.

A coil or circuit element will then be attached to the mounting board ina fashion to be described later, the leads thereof secured to the shortends 14 of the terminal wires, these ends soldered as by a dip, and thewhole mounting board then immersed in Durez and cured to obtain amounted coil like that of FIG. 1.

It will be appreciated that the attachment of the terminal wires to themounting board is not inherently as secure as the attachment of thestaple in the above described coil mount of the art. By deliberateeffort the terminal wires can be pulled out from behind the slot edges52. On the other hand the assembly is as strong as it need be. Theretention of the terminal wires is ample to permit a wrapping of thecoil leads thereabout without danger of displacement, and after theDurez dip and baking, the entire structure is cemented together into aunit which possesses ample characteristics of strength.

This limited strength requirement imposed on the terminal wire andmounting board connection during the mounted coil assembly suggestsother modes of attachment of the terminal wires to the mounting board.FIGS. 1 and 2 show another possible assembly technique. In this case theterminal wires 12 are fed transversely between two strips of appropriatepaper 54 having tacky gummed surfaces which face each other. Thereafterin a simultaneous pressing and blanking operation the wire may be cut tolength, the paper pressed so that the gummed surfaces thereof engageeach other encompassing the wires, and such punching and shearing doneas may be desired of the double paper layer. Thereafter the coil will beinserted, leads secured and the whole Durez-dipped as described before.

FIGS. 3 and 4 illustrate another modification of the coil mount whereinthe terminal wires are adhesively secured to a single sheet of the fishpaper. The paper may have a gummed side on which the terminal wires maybe laid transversely of the strip. Again the wires may be cut, pressedinto the gummed surface of the strip for firm connection and the papershaped as desired. The rest of the assembly then follows in order. Sucha procedure will serve well where the adhesive employed is a curablestrong type such as epoxy or polyester. Polyester and epoxy adhesiveshowever are expensive and require a separate operation and time forcuring.

To permit the use of ordinary contact cements we have devised the mountillustrated in FIGS. 3 and 4. It should be appreciated that the bond ofDurez to a cement coated surface is no stronger than the adhesion of thecement to that surface. Durez bonds much more strongly directly to thepaper than to ordinary contact cements. Therefore in the modification ofFIG. 3, rather than coating one entire side of the paper strip, we printlines 56 of contact cement where the terminal wires are to be placed andform windows 58 through the paper in the center of these lines, forinstance, slightly wider than the wire. The terminal wires, as before,are deposited on the glued strips. In the operation of cutting them tolength, the wires are dented down into the windows 58 as at 60. The glueretention will be sufficient to hold the terminal wires for themanipulations to be performed thereon in the course of assembling themounted coil. Thereafter the Durez coating bonds the wires closely tobare paper surfaces. There will be leakage of Durez through the windows58 and through the coil window 24 to bond the coatings of Durez on eachside of the paper together and to encase the terminal wire dents. TheDurez between the dents 60 and the window edges imposes manipulativeloads thereon upon the paper of the window edges thereby preventinglongitudinal shift of the wires within the Durez casing, and the Durezbetween the dents and the sides of the windows 58 prevents rotationaldisplacement of the terminal wires. It will be appreciated that thismodification demands that the dents 60 extend only into and not throughthe windows 58, and the coil mount may thus have an absolutely flatside.

FIGS. 5 and 6 illustrate another method of temporary terminal wireattachment to a mounting board which has particular advantages of itsown. In this modification we use a mounting board 10 of corrugated paperhaving the usual outer plies 63 and a corrugated middle ply 65supporting and spacing the outer plies. The corrugations leavethrough-apertures 67 that snugly receive the terminal wires 12. We findthe frictional engagement of the wires within the apertures normallysufficient to resist manipulation. Where the handling is particularlyvigorous, however, it may be advantageous to swage a flat 69 on thewires after their insertion to anchor them more securely. The cardboardrestores itself substantially after the swaging.

The advantage of this structure is that the mounting board is flat andthat the terminal wires are spaced from the planes of either of thefaces thereof. As a consequence, the entire face or faces of the boardis available for coil mounting and coils of substantially greaterdiameter can be accommodated. This should be compared with the mount ofFIGS. 7 and 8 where the coil is limited in diameter to the space betweenthe bights 38 or to the diagonal distance between the inside of theshort end 34 of one wire and the inside of the long end 36 of the other.

In FIG. 3 it should be noted that the short terminal wire ends 14 arepinched off rather than sharply sheared off so as to leave a flattenedpointed tip 62. This tip provides a shearing edge for the relativelyfine wire of the coil leads 26 so that the leads may be cut off afterwrapping on the terminal wire without the necessity for picking upanother tool. A detail such as this contributes greatly to speed ofassembly.

It should be further noted that the top and bottom edges 71 and 73 ofthe boards are notched as at 75. Both the short and long terminal wireends are usually immersed in a solder bath, the short ends to solder thecoil leads thereto and the long ends to tin them. Such dips present thepossibility of charring the top and bottom edges of the boards andcreating a conductive carbon path between the terminal wires. Thenotches 75 interrupt the continuity of these edges.

The remaining figures all relate to various ways in which a circuitelement such as a coil may be retained by the mounting board inpreference to the simple glue attachment as describe d above. Asindicated before the glued attachment has several disadvantages. Firstit is slow. Second, the strength of the Durez coating is reduced in thatit is not bonded to the whole surface of the mounting board.

FIGS. 13 through 19 illustrate a first form of temporary coil attachmentprior to the Durez dip. In all of these figures, the mounting board isshown without the terminal wires. It will be appreciated that theterminal wires may be attached in any of the fashions indicated in FIGS.2, 3, 5, or 7.

In the structures of FIGS. 14 through 19, a window 64 is formedcentrally in the board wherein two opposite edges have inwardlyprojecting central bulges or tongues 66. We contemplate that whateveruse this structure may have in mounting other circuit elements, it willhave particular utility in mounting an entire range of inductors. FIGS.15 and 16 illustrate the mounting of a high inductance coil 68. The coilconsists of a dumbbell shaped core 70, the central portion 72 of lessdiameter having a winding 74 thereon. The core is contained within asleeve 76 of ferromagnetic material to complete the magnetic circuit.The sleeve 76 is somewhat longer than the core. The fit of the corewithin the sleeve is loose enough so as to permit the winding leads 78to extend out between one of the dumbbell ends and the inside wall ofthe sleeve 76. The assembly is easy and rapid. The wound core isinserted in the sleeve and the sleeve then snapped into the window, thetongues 66 engaging the ends of the sleeve 76. The tongues and windowgenerally are fitted to the longitudinal central section of the sleeveso that the sleeve extends out from the mounting board half on one sideand half on the other. The tongues 66 extend a short distance into theopen ends of the sleeve and bear against the ends of the core to centerit longitudinally within the sleeve. Thus a complete mounted coil may beprovided by snapping the high inductance coil into the window of themounting board, the terminal wires being already attached, twisting thecoil leads 78 to the short ends of the terminal wires, solder-dippingthe short terminal wire ends, dipping the entire mounting board in aDurez dip and baking.

The same general type window may be employed for mounting a lowinductance coil as illustrated in FIG. 17 and largely described above.Here, the coil 18 consists of a single layer winding on a tubularcardboard form 22. The coil 18 is snapped into the window so that thetongues 66 extend into the open form ends 86 and support the coil firmlywithin the window. Again the coil leads are attached to the terminalwires, solderclipped, and the whole Durez coated.

FIGS. 18 and 19 illustrate the same general concept as applied to amedium inductance coil. Here the coil 88 is a universally wound, washershaped coil without a core. Again the window 64 is formed to conform tothe cylinder sides or central longitudinal section of the coil, andtongues 66 are provided in the opposite windows sides conforming to theends of the coil. Again, the coil is snapped into the window so that thetongues 66 extend into the central aperture 92 of the coil 88 to anchorit into the window. The mounting coil is then finished as described.

FIGS. 20 through 23 illustrate another window whereby a variety ofcircuit elements may be variously contained in a mounting board withoutthe necessity of gluing. In this form, the mounting board is cutcentrally across its top and bottom ends as at 94 and a centerconnecting cut 96 is made between them so as to define a pair of flaps98. The flaps 98 may be appreciably longer than the coil to becontained. In FIG. 21 is shown a universally wound coil 100 like that inFIG. 19 inserted between the flaps 98 to spring them out so that theflap edges bear against the ends of the coil. The material of themounting board is stiffly resilient and will support the coil firmly.

If the lateral extension of the coil of FIG. 21 is not wanted, the flaps98 can be opened oppositely and the coil 100 inserted between them asparticularly illustrated in FIG. 22. The opposite opening of the flapslikewise serves to mount tubular form wound coils 102 as best seen inFIG. 23.

All of these mounting configurations illustrated in FIGS. 14- through 23possess the advantages, first, of exceedingly quick assembly; second,the use of no glue to retard manufacture and to impair the adhesion ofthe Durez to the mounting board material; and third, of permittingleakage of the Durez suspension around the coil or circuit elementbetween opposite sides of the mounting board to integrate the Durezcoatings on the two sides of the board.

FIGS. 24 and 25 illustrate a method of using the mount of the inventionfor supporting and connecting a tunable coil. To this end we form acentral circular aperture 104 in the center of the mounting board whichis smaller in diameter than the coil itself. The edges of the apertureare slit or broken as at 106 to provide a ring of infacing tongues. Thecoil 108, on a tubular form, may be inserted into the aperture, thetongues holding the coil firmly so as to extend transversely of themounting board with the bore of the form and consequently the exposedtuning slug 110 readily accessible. Ifa Durez coating is desired, thecore ends may be capped for dipping.

FIGS. 26 and 27 illustrate the use of the coil mount of the invention ina four terminal context. In this situa tion we provide two coil mounts111, each having a central bore 112 therein. The coil or transformer 114proper may be wound on a tubular form 116 having an interior diameterequal to the diameter of the bores 112. The mounts thus will be buttedup against the ends of the form. A tubular sleeve I18 somewhat longerthan the form 116 is contained in the form and extends beyond it ateither end through and beyond the mounts III and is rolled overoutwardly at its ends to provide flanges 120 which secure the assemblytogether. It will be appreciated that since two mounts are employed,there will be four terminal wires thus adapting the structure to suchfour terminal purposes as the mounting of transformers, etc. The sleeve118 is open throughout and therefore adapted to receive a metal core orslug if desired.

FIGS. 28 and 29 illustrate a six terminal structure. In this instance,the mount I24 consists of alternating narrow 126 and wide 128 elementsconnected together but scored as at 129 for folding.

The board can thus be folded into a rectangular configuration asillustrated in FIG. 29, the narrow sections 126 constituting the endsand the wide sections 128 constituting the sides. The narrow sections126 each have a central terminal wire 130 mounted therein and the wideor side sections 128 have a pair of spaced terminal wires 131 in thefashion of the simple mounts. The terminal wires may be attached to themount board in any of the fashions described above, although that methodshown in FIG. 7 is illustrated. The six terminal element 132, possiblyin the form of a universally wound coil, will be glued to one of thewide members of the mount and the other sides folded thereabout. Theopposite wide side should also have adhesive applied thereto in order tomaintain the shape of the folded mount and further support the element.

It will be appreciated here that while the windowed mounting boardsillustrated in FIGS. 14 through 25 have definite advantages in the speedand inexpensiveness of assembly, there may be instances where theadditional expense and time consumption of the gluing operation arejustified. It is not our invention, therefore, to exclude necessarily aglued attachment of the circuit element to any of the board structuresillustrated in FIGS. 1 through 8, although for most purposes thewindowed structures will be preferred.

FIG. 30 illustrates a coil mount 132 of the invention serving also as aform for a low inductance coil. Here the mounting board 134 is formed tobe generally rectangular with shoulders 136 extending above and belowthe board on each side thereof. The terminal wires 138 will be centeredin the shoulders. Thereafter the appropriate number of turns of coilwire 140 are wrapped around the central portion of the mounting board between the shoulders 136 and secured to the short terminal wire ends 142in the fashion described. The shoulders serve to space the coil wirefrom the terminal wires and avoid unwanted shorting. The shoulders alsodefine an index to the solder dip and the tinning clip so that the coilwire 140 on the board will not be exposed to solder immersion.

It will be appreciated from the foregoing description of the manymodifications of the invention that we have devised a coil mount and amounted coil suitable for insertion into electric circuits, particularlyof the printed circuit kind, which represents a notable advance overanything known in the art. It is simple, inexpensive, occupies littlespace, and is exceedingly flexible in its application. The speed andease of manufacture of such circuit components embodying the inventionare notable. It will be further appreciated that although we havedescribed several specific embodiments of the invention it is not to beregarded as being limited only to those shown. Others undoubtedly willsuggest themselves and we desire, therefore, that out invention beregarded as being limited only as set forth in the claims hereof.

In the claims, the term untrimmed" is used as defining terminal wirelengths. As described above, the staple insertion of the terminal wiresinto a mounting board limits the ends of the terminal wires torelatively short lengths and demands that they be of equal length. Itwill be appreciated that an unequal length of leg could be obtainedsubsequently by cutting one of the legs of each of the staples evenshorter. This is, however, wasteful of terminal wire, requires anadditional operation, and still does nothing to extend the possiblelength of the other leg. The legs of the terminal wires of the inventioncould be defined as long to distinguish over the staple type, and insome instances are, but this is a characterization lacking indefiniteness. More definite is the characterization of the terminalwires being unequal initially or without a subsequent trimming orshortening operation.

We claim:

1. An inductive circuit element comprising a winding having at leastthree leads for independent circuit connection, stiff insulatingparallel panels mounted on opposite sides of said winding, each of saidpanels having a pair of stiff terminal wires extending thereacrossadjacent opposite edges thereof and beyond said panels at each end, allof said wires being parallel, the ends of said wires extending in onedirection being adapted for insertion in a printed circuit board, saidleads being secured to the other ends of said wires.

2. The combination as set forth in claim 1 wherein said windingincorporates a coil form and said panels are mounted to said coil formbeyond opposite ends of said winding.

3. An inductive circuit element comprising a winding having at leastthree leads for independent circuit connection, a strip of relativelystiff insulating material folded about at least three sides of saidwinding to define at least parallel side portions and an end portionembracing and supporting said winding, means securing said side portionsagainst said coil, said strip having at least three relatively stiffterminal wires extending transversely thereacross and beyond the edge ofsaid strip at both ends, said terminal wires occupying at least two ofsaid portions, the ends of said wires extending from one side of saidstrip being adapted for circuit connection and the leads of said windingbeing secured to the other ends of said terminal wires.

1. An inductive circuit element comprising a winding having at least three leads for independent circuit connection, stiff insulating parallel panels mounted on opposite sides of said winding, each of said panels having a pair of stiff terminal wires extending thereacross adjacent opposite edges thereof and beyond said panels at each end, all of said wires being parallel, the ends of said wires extending in one direction being adapted for insertion in a printed circuit board, said leads being secured to the other ends of said wires.
 2. The combination as set forth in claim 1 wherein said winding incorporates a coil form and said panels are mounted to said coil form beyond opposite ends of said winding.
 3. An inductive circuit element comprising a winding having at least three leads for independent circuit connection, a strip of relatively stiff insulating material folded about at least three sides of said winding to define at least parallel side portions and an end portion embracing and supporting said winding, means securing said side portions against said coil, said strip having at least three relatively stiff terminal wires extending transversely thereacross and beyond the edge of said strip at both ends, said terminal wires occupying at least two of said portions, the ends of said wires extending from one side of said strip being adapted for circuit connection and the leads of said winding being secured to the other ends of said terminal wires. 